Tunable electromagnetic environment for superconducting quantum bits

TL;DR

This paper presents a tunable environment for superconducting qubits using coupled cavities with controllable dissipation and coupling strength, enabling rapid initialization and unhindered evolution of the qubit.

Contribution

It introduces a novel setup with SQUIDs for adjustable coupling and dissipation control in circuit QED, enhancing qubit manipulation capabilities.

Findings

Controlled dissipation via a resistor in a cavity environment.

Tunable coupling strength using SQUIDs.

Rapid qubit initialization and reduced decoherence.

Abstract

We introduce a setup which realises a tunable engineered environment for experiments in circuit quantum electrodynamics. We illustrate this concept with the specific example of a quantum bit, qubit, in a high-quality-factor cavity which is capacitively coupled to another cavity including a resistor. The temperature of the resistor, which acts as the dissipative environment, can be controlled in a well defined manner in order to provide a hot or cold environment for the qubit, as desired. Furthermore, introducing superconducting quantum interference devices (SQUIDs) into the cavity containing the resistor, provides control of the coupling strength between this artificial environment and the qubit. We demonstrate that our scheme allows us to couple strongly to the environment enabling rapid initialization of the system, and by subsequent tuning of the magnetic flux of the SQUIDs we may greatly reduce the resistor-qubit coupling, allowing the qubit to evolve unhindered.